Croatia, Bosnia, Montenegro Travel - Most Efficient Option

Rovinj is out of the way. And with Korcula you will be visiting a similar town. So I would concentrate in exploring what the area has to offer, and not ticking of boxes...
When we were in Dubrovnik we also had the idea of doing day trips to further away places, but never got around doing that. There is so much to see in the immediate surroundings. How many weeks are you going?

Regarding a logical order: You could do of course do an open jaw, fly to Split, and back from Dubrovnik. Failing that, just travel to Split by bus, and then island hop back to Dubrovnik.

Okay, two trips with just shy of 2 weeks in Croatia and still not one of my favorite places, so this will be a bit jaded. On the other hand Montenegro is heaven.

As mentioned elsewhere do it open jaw, but I would arrive Split and depart from Podgorica, and not Dubrovnik.

Here is the way I would do it: https://maps.app.goo.gl/AmwuQtBvKhpwbhcm7

You didnt say how you were traveling so I also suggest you hire a driver. At least in Montenegro where things are sitll cheap. Money very well spent. Personally I would spend a few hundred dollars and have someone like Dinana plan the whole trip.

Dijana Krkotic
Guide & Tour Designer
Doclea Travel
+382 69 277 749
dijana@docleatravel.com
www.docleatravel.com

From Dubrovnik you can do daytrip to Kotor, also from Dubrovnik you can take catamaran to Korcula, then catamaran to Hvar, catamaran to Split. From Split to Dubrovnik you can have private transfer with stop in Mostar. Also you can check for bus on this route especially if you have time for spend the night there.
Rovinj is little bit far away since you are fly in and out from Dubrovnik.
In case that you need private transfer you can check here https://private-experience-croatia.com/tour/transfer-split-to-dubrovnik/

You don’t say how much time you have - which is kind of important when talking about what you can fit in. That being said, Rovinj is a real outlier so I would skip this time.

If you are already stuck flying in and out of Dubrovnik, then I might land and head straight to Korcula (easy bus or taxi airport to the port upon arrival), then Hvar, then Split, all by catamaran. Then via car or driver, go to Mostar, followed by Kotor and then on to Dubrovnik for your stay there.

This gives you more lodging stops, but it also gives you more views of gorgeous Montenegro - the mountains as well as the coast that you will see in Kotor. Somehow it makes no sense to me to pay the high price of lodging in Dubrovnik while you spend 2 days headed to far less expensive places. Overnights in these cities will give you a better view of them, as well as letting you see more (with the same amount of total overnight stops).

Dijana can also set you up with a driver if you don’t want to drive yourself. Email her to ask cost - the website isn’t as helpful.

Have you said how long you have? That would determine if Rovinj is an option, but it is awfully far from your other destinations.
Are you open to renting a car?
Without a car, you could go to Montenegro and back, then head north by sea and return by bus via Mostar.
You can get from Dubrovnik to Korcula via bus (bus takes ferry) or catamaran. Continue to Hvar and Split by catamaran, bus from Split to Mostar, bus to Dubrovnik.
See boat schedules on the Jadrolinija and Krilo websites.

Personally, I would make a circle starting in Dubrovnik, bus, rental car, or driver to Mostar, same to Split, drop off car if rented. Then catamaran to Hvar, same to Korcula, same to Dubrovnik. From Dubrovnik you can take a day tour to Kotor. Rick recommends one in his book - Dubrovnik Rivera tours. We used them to go to Cavtat for the day.